1. field of the invention
This invention relates to spherical poppet valves, and more particularly to the type of valve wherein a spherical valve poppet is pivotably mounted within a spherical valve casing for rotation from a first axially in-line position with respect to an annular valve seat to a second valve open position at an angle thereto and outside of the axial flow path through the seat opening.
2. DESCRIPTION OF THE PRIOR ART
Spherical poppet valves of a sophisticated nature have evolved within the past few years wherein a cylindrical valve body includes a semi-spherical pocket outside of the axial flow path through the cylindrical valve body and a spherical valve poppet is pivotably mounted within the body for rotation from a first axially in-line position with respect to an annular valve seat adjacent the pocket to a second valve open position at an angle thereto with the valve poppet outside of the axial flow path through the seat opening. Spherical poppet valves of this general type form the subject matter of U.S. Pat. No. 3,675,894 issuing July 11, 1972, and copending application Ser. No. 448,439 filed Mar. 5, 1974, assigned to the common assignee. The spherical poppet valves are characterized by means which spring bias the spherical valve poppet into contact with the annular valve seat when in alignment therewith by a lateral or translation movement towards the seat opening along the axial flow path of the fluid passing through the valve housing or casing, under control of an eccentric. Shaft means are employed for effecting rotation of the valve poppet after retraction slightly from the valve seat, from a position axially aligned with respect to the valve seat to a rotated position at some angle thereto with the poppet positioned outside of the axial flow path and within the spherical pocket of the valve casing.
The spherical poppet valves referred to above have their sequence control mechanism exposed to the fluid being handled by the valve, and this prevents optimum lubrication of these parts. Attempts have been made to employ O-rings, seals or the like, but these are not compatible with all fluids, and rotating seals are not completely leak-tight. Therefore, leaks can damage the motors or may be otherwise dangerous, particularly where the valves are employed in sophisticated fluid systems. Irregular valve flow areas cause excessive pressure drop in critical applications, the irregular flow valve areas being partially created by the presence of the sequence control mechanism.